Junction FET semiconductor device with dummy mask structures for improved dimension control and method for forming the same

ABSTRACT

A method for semiconductor devices on a substrate includes using gate structures which serve as active gate structures in a MOSFET region, as dummy gate structures in a JFET region of the device. The dummy gate electrodes are used as masks and determine the spacing between gate regions and source/drain regions, the width of the gate regions, and the spacing between adjacent gate regions according to some embodiments, thereby forming an accurately dimensioned transistor channel.

RELATED APPLICATION

This is Continuation Application of U.S. patent application Ser. No.14/881,006, filed on Oct. 12, 2015, which is a Divisional Application ofU.S. patent application Ser. No. 13/861,523, filed on Apr. 12, 2013,which claims priority to U.S. provisional patent application Ser. No.61/781,955 filed Mar. 14, 2013, the contents of which are incorporatedby reference herein in their entireties.

TECHNICAL FIELD

The disclosure relates, most generally, to semiconductor devices andmethods for manufacturing the same. The disclosure relates, moreparticularly, to JFET and MOSFET devices and methods for forming JFETand MOSFET devices with self-aligned features and superior dimensioncontrol.

BACKGROUND

A junction field effect transistor (JFET, also known as junction gatefield effect transistor) is a semiconductor transistor formed in asemiconductor substrate and the current that flows in a JFET iscontrolled by electrodes made of P-N junctions formed in thesemiconductor substrate. The gate electrode is one such P-N junctionformed in the semiconductor substrate. Gate voltage is applied to atransistor channel across the P-N junction of the gate electrode andthis controls the current going from source to drain. To turn off thetransistor by pinching off the current flow, the gate-to-source voltageis controlled. To pinch off current in an N-channel JFET, a negativegate-to-source voltage is applied and to pinch off current flow in aP-channel JFET, a positive gate-to-source voltage is applied.

Junction field effect transistors have relatively long channels comparedto MOSFET (Metal Oxide Semiconductor Field Effect Transistor) devices.In JFET transistors, the source and drain regions are not immediatelyadjacent the gate region or separated from the gate region by an LDD(lightly doped drain) region. Rather, the gate region in the substrateis separated from the source and drain regions also formed in thesubstrate. The transistor channel is a current path from the source tothe drain as activated by the gate and therefore it is especiallycritical to position the source, drain and gate regions accurately sothat they are accurately spaced apart by the desired spacing and adesired channel length is achieved.

The source and drain and gate regions are typically formed by separatepatterning and ion implantation operations that introduce dopantimpurities into the substrate and the separate patterning operationseach carry with them a degree of alignment and placement inaccuracy. Anyinaccuracy impacts the channel length which is designed in conjunctionwith the voltage to be applied to the gate. Therefore, if the gate isnot spaced accurately from the source and the drain resulting in anundesired channel length, the transistor will not function properlyusing the desired voltage.

It is therefore desirable to produce transistors such as JFET's thathave accurately aligned and carefully spaced features.

BRIEF DESCRIPTION OF THE DRAWING

The present disclosure is best understood from the following detaileddescription when read in conjunction with the accompanying drawing. Itis emphasized that, according to common practice, the various featuresof the drawing are not necessarily to scale. On the contrary, thedimensions of the various features may be arbitrarily expanded orreduced for clarity. Like numerals denote like features throughout thespecification and drawing.

FIGS. 1-6 are cross-sectional views showing a sequence of processingoperations according to an embodiment of the disclosure;

FIG. 7 is a cross-sectional view showing an embodiment of adjacent JFETtransistor devices formed according to an embodiment of the disclosure;

FIG. 8 is a cross-sectional view showing an embodiment of a JFET withmultiple gates according to an embodiment of the disclosure;

FIG. 9 is a cross-sectional view showing another embodiment of a JFETaccording to an embodiment of the disclosure; and

FIG. 10 is a cross-sectional view showing aspects of another embodimentof a JFET according to an embodiment of the disclosure.

DETAILED DESCRIPTION

The disclosure provides for forming various types of JFET (junction gatefield effect or junction field effect transistor) devices. The JFETtransistors are formed using a sequence of processing operations thatsimultaneously form other devices such as MOSFET (metal oxidesemiconductor field effect transistor) devices and other semiconductordevices on other regions of the same substrate. According to oneembodiment, gate structures are formed over the substrate in both JFETand MOSFET regions and the gate structures serve as active transistorgates for the MOSFET devices and serve as dummy gates in the JFETregion. In the JFET region, the dummy gates accurately establish thespacing between the gate region and the source/drain regions andtherefore the transistor channel length and other structures serve asthe actual transistor gates.

FIG. 1 shows two substrate portions: N-channel JFET portion 1 andN-channel MOSFET portion 2. Both N-channel JFET portion 1 and N-channelMOSFET portion 2 are formed in the same substrate, P-type substrate 3 asindicated by substrate surface 9 and the breakaway lines. In someembodiments, both N-channel JFET portion 1 and N-channel MOSFET portion2 form parts of an integrated circuit device formed on the substrate. Inother embodiments, P-channel JFET devices and P-channel MOSFET devicesare formed in various dopant regions in a substrate including in asingle integrated circuit or other semiconductor device. N-channel JFETportion 1 and N-channel MOSFET portion 2 are formed in the samesubstrate which is subjected to the sequence of processing operationsthat simultaneously form features of N-channel JFET portion 1 andN-channel MOSFET portion 2. In FIG. 1, N-channel JFET portion 1 andN-channel MOSFET portion 2 each include N-wells 5 and P-wells 7 formedin P-type substrate 3. STI structures (shallow trench isolationstructures) 11 extend downwardly from substrate surface 9.

Although the disclosure is described in conjunction with the illustratedN-channel JFET portion 1 and N-channel MOSFET portion 2, aspects of thedisclosure are also used to form P-channel JFET devices and P-channelMOSFET devices in other embodiments. In such other embodiments, thepolarity of the various well portions will differ.

FIG. 2 shows the structures of FIG. 1 after a processing operation hasbeen carried out to form gate electrodes over a gate dielectric. Thegate electrodes include dummy gate electrodes 19D in N-channel JFETportion 1 and active gate electrodes 19A in N-channel MOSFET portion 2.Gate dielectric 21 is interposed between the gate electrodes 19D and19A, and substrate surface 9 and is formed of various suitabledielectric materials and various embodiments. Various photolithographicand etching operations are available and are used to form the structureincluding gate electrode 19D or 19A and gate dielectric 21 in variousembodiments. In one embodiment, gate electrodes 19D and 19A are formedof polycrystalline silicon (“polysilicon”) and in other embodiments,other suitable gate electrode materials are used. In N-channel JFETportion 1, gate electrodes 19D serve as dummies, i.e. they are notfunctional but they are used as masks to accurately establish thespacing between critical JFET device features. Gate electrodes 19A areactive gate electrodes that will serve as gate electrodes for operableMOSFET devices.

Because active gate electrodes 19A are formed in N-channel MOSFETportion 2 to serve as transistor gates, and because N-channel JFETportion 1 and N-channel MOSFET portion 2 are formed on the samesubstrate, no additional processing operations are required to formdummy gate electrodes 19D in N-channel JFET portion 1.

FIG. 3 shows the structures of FIG. 2 after sidewall spacers have beenformed along gate electrodes 19D and 19A and a photoresist pattern hasbeen formed as well.

Sidewall spacers 25 are formed along each of opposed sidewalls 23 ofactive gate electrodes 19A and dummy gate electrodes 19D. Sidewallspacers 25 are formed of oxide, nitride, oxynitride or a compositestructure formed of multiple dielectric materials. Various proceduresfor forming sidewall spacers 25 are used in various embodiments. In oneembodiment, a dielectric layer is conformally deposited over thestructure shown in FIG. 2 and an anisotropic etching operation iscarried out to form sidewall spacers 25. Other methods are used in otherembodiments. Dummy gate structures 27D each include a dummy gateelectrode 19D, sidewall spacers 25 and gate dielectric 21. Active gatestructures 27A each include an active gate electrode 19A, sidewallspacers 25 and gate dielectric 21

FIG. 3 also shows photoresist pattern 29 in both N-channel JFET portion1 and N-channel MOSFET portion 2. It can be seen that photoresistpattern 29 is formed over portions of dummy gate structure 27D and overactive gate structure 27A. In the illustrated embodiment showing theformation of N-channel devices, photoresist pattern 29 along with dummygate structures 27D and active gate structure 27A serves as a P+source/drain mask that includes openings through which P+ dopants areintroduced. Arrows 35 indicate the dopant impurities being introduced byway of ion implantation or other suitable means for introducing dopantimpurities into the substrate. FIG. 3 also shows P+ regions formedwithin the substrate including P+ gate region 31 and other P+dopantregions 33 as a result of the ion implantation or other suitable meansfor introducing dopant impurities into the substrate. It can be seenthat the location of P+ gate region 31 in N-channel JFET portion 1 isdetermined and defined by dummy gate structures 27D. P+ gate region 31is self-aligned with respect to dummy gate structures 27D. Statedalternatively, the position of P+ gate region 31 within N-well 5 isdetermined by the facing edges of opposed dummy gate structures 27D, andnot photoresist pattern 29. The lateral edges of P+ gate region 31coincide with the lateral edges of dummy gate structures 27D.

Photoresist pattern 29 is removed using various methods in variousembodiments. After photoresist pattern 29 is removed, a furtherphotoresist pattern is formed as shown in FIG. 4

FIG. 4 shows the structures of FIG. 3 after a further photoresistpatterning processing operation has been carried out. Photoresistpattern 43 is formed using various photolithographic operations. In theillustrated embodiment of N-channel JFET portion 1 and N-channel MOSFETportion 2, photoresist pattern 43 along with dummy gate structures 27Dand active gate structure 27A serves as an N+ source/drain photoresistpattern and includes openings through which N+ dopants are introduced.Arrows 39 indicate the dopant impurities being introduced by way of ionimplantation or other suitable means for introducing dopant impuritiesinto the substrate.

FIG. 4 also shows N+ regions including N+ source/drain regions 47 formedwithin the substrate as a result of the ion implantation or othersuitable means for introducing dopant impurities into the substrate.During the processing operations used to introduce dopant impurities andform both P+gate region 31 and N+ source/drain regions 47, the locationsof the impurity regions are determined by dummy gate structures 27D andactive gate structures 27A serving as mask features. Both N-channel JFETportion 1 and N-channel MOSFET portion 2 include N+ source/drain regions47. It can be seen that the placement of N+ source/drain regions 47 inN-channel MOSFET region 2 are self-aligned with respect to the gate,i.e. active gate structure 27A. It can also be seen in N-channel JFETportion 1 that the placement of N+ source/drain regions 47 in N-well 5is determined and defined by dummy gate structures 27D serving as masks.The edges of N+ source/drain regions 47 are coincident with the edges ofdummy gate structure 27D. Referring to N-channel JFET portion 1 in FIG.4, the transistor channel is the path between the source/drain regions,i.e. the path between the N+ source/drain regions 47 that flank P+ gateregion 31. In N-channel JFET portion 1, the spacing between P+ gateregion 31 and each N+ source/drain region 47 is determined by thedimensions of dummy gate structure 27D. It can be seen that N+source/drain region 47 on the left-hand side of P+ gate region 31 isspaced from P+ gate region 31 by length 49L and the N+ source/drainregion 47 on the right-hand side of P+ gate region 31 is spaced from P+gate region 31 by spacing 49R. Each of spacing 49L and 49R is determinedby the maximum lateral dimensions of dummy gate structures 27D servingas masks. For example, spacing 49R represents the length of thesource/drain-gate gap region on the right-hand side of P+ gate region 31and is equal to the maximum lateral width of dummy gate structure 27D,which is on substrate surface 9 and occupies the entire region ofsource/drain-gate gap region. As such, spacing 49L and spacing 49R areeach determined by the dimensions of dummy gate structures 27D and notthe photoresist pattern.

FIG. 5 shows the structure of FIG. 4 after photoresist pattern 43 hasbeen removed and after a silicidation operation has been subsequentlycarried out. As a result of the silicidation operation, silicide layer51 is formed on exposed silicon portions according to the embodiment inwhich P-type substrate 3 is a silicon substrate. Silicide layer 51 isformed over dummy gate electrodes 19D and active gate electrode 19A andthe top, exposed portions of P+ gate region 31, P+ dopant regions 33, N+source/drain regions 47 and other exposed portions of substrate surface9 such as the other illustrated N+ dopant impurity regions. Platinum andvarious other suitable metals are used to form silicide layer 51 invarious embodiments. Because the location of the silicide layers 51 isself-aligned with respect to dummy gate structures 27D and active gatestructure 27A, the silicidation process may be referred to as a salicide(“self-aligned silicide”) process.

Spacing 49L represents a source/drain-gate link region and dummy gatestructure 27D occupies the entire source/drain/gate-link region.Similarly, spacing 49R represents another source/drain-gate link regionand dummy gate structure 27D occupies the entire source/drain-gate linkregion.

FIG. 6 shows the structures of FIG. 5 after a dielectric and contactstructures have been formed. Dielectric 53 is formed over the structuresof FIG. 5 and various contact structures are formed through dielectric53 and down to the subjacent device features. Various methods andsuitable materials are used to form dielectric 53 in variousembodiments. Referring to N-channel JFET portion 1, gate contact 55 iscoupled to P+ gate region 31, source/drain contacts 57 are coupled to N+source/drain regions 47 and P+ contacts 59 are coupled to P+ dopantregions 33.

In N-channel MOSFET portion 2, the contact to active gate structure 27Ais not shown in FIG. 6. Source/drain contacts 63 are coupled to N+source/drain regions 47 and P+ contacts 65 are coupled to P+ dopantregions 33. Various suitable metals such as copper and aluminum or othersuitable conductive materials are used for the various contacts invarious embodiments. Various materials are used to form dielectric 53 invarious embodiments and the various contact structures are formed usingvarious methods.

The N-channel JFET shown in N-channel JFET portion 1 includes P+ gateregion 31 functioning as the transistor gate, and N+ source/drainregions 47 serving as source/drain regions. The transistor channelextends from one N+ source/drain region 47 to the other N+ source/drainregion 47. The channel length is the distance between N+ source/drainregions 47 that flank P+ gate region 31 and therefore a function of thespacings 49L and 49R between P+ gate region 31 and the N+ source/drainregions 47, and the width of P+ gate region 31 which was also determinedby dummy gate structures 27D serving as masks.

FIG. 7 shows two adjacent N-channel JFET devices. Each JFET deviceincludes an associated P+ gate region 31 and two N+ source/drain regions47 serving as source and drain regions. The two JFET devices share acommon drain—centrally located N+ source/drain region 47 withsource/drain contact 57 also identified as “Drain” in the illustrationof FIG. 7. Each JFET device includes a channel length determined by thespacing between P+ gate region 31 and the two N+ source/drain regions 47and the width of P+ gate region 31. In the JFET device illustrated onthe right-hand side of FIG. 7, the channel length is determined, in partby spacing 61 and spacing 62 between P+ gate region 31 and N+source/drain regions 47. Each spacing 61 and 62 is determined by and isequivalent to, the width of the associated overlying dummy gatestructure 27D on the substrate surface. The two JFET devices that sharethe common drain structure are also identified by their channels. TheJFET device on the left-hand side of FIG. 7 includes channel 71L and theJFET device on the right-hand side of FIG. 7 includes channel 71R.

FIG. 8 shows another aspect of the disclosure and illustrates anembodiment of a JFET structure with a multiple gate arrangement. Each ofthe three P+ gate regions 31 represents a gate or a portion of a gateincluding three P+ gate regions 31 and the JFET structure shown in FIG.8 also includes opposed N+ source/drain regions 47 which serve as sourceand drain regions. Channel length 75 is the distance between the opposedN+ source/drain regions 47. Each of the P+ gate regions 31 is spacedapart from one another by distance 77 which is equal to the width of thecorresponding dummy gate structure 27D. The width of the correspondingdummy gate structure 27D also establishes spacing 78 between theoutermost P+ gate region 31 and the adjacent N+ source/drain region 47serving as a source or drain. In each of FIGS. 7 and 8, dummy gatestructures 27C are not active structures.

Now turning to FIG. 9, another embodiment of a JFET device according toan embodiment of the disclosure is shown. JFET structure 79 includes agate including P+ gate region 31 and gate contact 55. JFET structure 79includes N+ source/drain regions 47 with source/drain contacts 57.Channel length 81 is determined by spacing 83 between P+ gate region 31and adjacent N+ source/drain region 47 and the width of P+ gate region31. In the embodiment of FIG. 9, spacing 83 is determined by two dummygate structures 27D plus a blocking film 85 that extends betweenadjacent dummy gate structure 27D and partially over each dummy gatestructure 27D. Blocking film 85 is a resist protect oxide, RPO, in oneembodiment but other suitable blocking films are used in otherembodiments. According to this embodiment, both dummy gate structures27D and blocking film 85 are in place when the implantation or otherdopant impurity introduction operations are used to form P+ gate region31 and N+ source/drain regions 47. In the embodiment illustrated in FIG.9, the location of P+ gate region 31 and the two N+ source/drain regions47, as well as the spacing between these components, is determined by amasking structure made up of dummy gate structure 27D and blocking film85, i.e. not by a photoresist pattern.

FIG. 10 shows an embodiment of JFET device 89 with P+ gate region 31 andtwo N+ source/drain regions 47 serving as the source and drain regions.The embodiment of FIG. 10 shows dopant extension regions 91 and 93.Dopant extension region 91 is a P+ region extending from P+ gate region31 and is formed using angled ion implantation or using thermaldiffusion operations. Dopant extension region 93 is also foamed usingangled ion implantation or using thermal diffusion operations and is anN+ region extending from N+ source/drain regions 47. In someembodiments, dopant extension regions 93 are considered LDD, lightlydoped drain, regions. Each of dopant extension regions 91 and 93 areformed by first forming the associated dopant region, ie P+ gate region31 or N+ source/drain region 47 as defined using dummy gate structure27D as a mask then using angled ion implantation or other thermaldiffusion operations to cause encroachment.

In the embodiment of JFET device 89 shown in FIG. 10, the placement andwidth of P+ gate region 31 and the two N+ source/drain regions 47 aredetermined by dummy gate structures 27D used as a mask.

According to the various embodiments, various JFET devices are formedusing a sequence of processing operations that also simultaneously formMOSFET devices in other portions of the substrate. The JFET devices arecharacterized by having their gate portions and source/drain portionslocated and spaced apart by a dummy gate structure serving as a mask Thedummy gate structure serving as a mask further provides the width of theP+ gate region.

In other embodiments, P-channel JFET and MOSFET devices are formed usingsimilar techniques as described above but using substrate portions anddopant impurities with different polarities.

In one embodiment, provided is a semiconductor device comprising: asubstrate; a JFET transistor comprising a gate region of one polaritydisposed in the substrate and source and drain regions of oppositepolarity also disposed in the substrate and spaced apart from the gateregion, wherein the source region is spaced apart from the gate regionin the substrate by a source-gate link region having a length “a” andthe drain region is spaced apart from the gate region in the substrateby a drain-gate link region having a length “b;” a dummy gate structuredisposed over a surface of the substrate and having a maximum widthequal to the width “a;” and a further dummy gate structure disposed overthe surface and having a maximum width equal to the width “b”.

In one embodiment, width “a” is substantially the same as width “b”.

In one embodiment, the dummy gate structure occupies the entiresource/gate link region and the further dummy gate dielectric occupiesthe entire drain/gate link legion and a width of the gate region equalsa spacing between the dummy gate structure and the further dummy gatestructure.

In one embodiment, the dummy gate structure includes a polysilicon gateelectrode.

In one embodiment, the dummy gate structure further includes sidewallspacers along sidewalls of the polysilicon gate electrode.

In one embodiment, the semiconductor device further comprising asilicide on top surfaces of the gate region, the drain region and thesource region and on top of a gate electrode portion of the dummy gatestructure.

In one embodiment, the gate electrode portion is formed of polysiliconand the dummy gate structure further includes sidewall spacers alongsidewalls of the polysilicon gate electrode portion.

In one embodiment, the dummy gate structure comprises a duality of gateelectrodes with sidewall spacers, spaced apart from one another by aspacing and wherein the spacing and at least part of each the gateelectrode is covered by a blocking film layer, and wherein the furtherdummy gate structure comprises a duality of further gate electrodes withsidewall spacers, spaced apart from one another by a further spacing andwherein the further spacing and at least part of each the further gateelectrodes is covered by the blocking film layer

In one embodiment, provided is a semiconductor device comprising: asubstrate; a JFET transistor comprising at least one gate region of afirst polarity disposed in the substrate and source and drain regions ofa second polarity also disposed in the substrate and spaced apart fromthe at least one gate region, wherein the source region is spaced apartfrom the at least one gate region in the substrate by a source-gate linkregion and the drain region is spaced apart from the at least one gateregion in the substrate by a drain-gate link region; at least one dummygate structure disposed over a surface of the substrate and havingopposed ends extending from an edge of the drain region to an edge ofthe at least one gate region; and at least one further dummy gatestructure disposed over the surface and having opposed ends extendingfrom an edge of the source region to an edge of the at least one gateregion.

In one embodiment, each dummy gate structure comprises a polysilicongate electrode with sidewall spacers and the at least one dummy gatestructure comprises a plurality of dummy gate structures with an oxideextending between the dummy gate structures and over a top of the dummygate structures.

In one embodiment, the at least one gate region comprises a plurality ofdiscrete gate regions formed in the substrate, and wherein adjacent gateregions of the plurality of discrete gate regions are spaced apart by agate—gate link region and wherein a further dummy gate structure isdisposed over the surface and includes a maximum width equal to a widthof the gate-gate link region.

In one embodiment, provided is a method for forming a semiconductordevice. The method comprises forming a dopant region of a first polarityin a substrate; forming at least a duality of dummy gate structures overthe dopant region, each the dummy gate structure including a gateelectrode with opposed sidewall spacers; using the dummy gate structuresas masks and introducing dopant impurities of a second polarity into thedopant region between at least two of the duality of dummy gatestructures thereby forming at least a gate structure in the substrate,each gate structure having a width equal to the spacing between theduality of dummy gate structures; using the dummy gate structures as amask and introducing dopant impurities of the first polarity into thedopant region in areas laterally outside and immediately adjacent thegate structures thereby forming a duality of source/drain regions in thesubstrate; and forming a JFET by forming contacts to the gate structureand the source/drain regions.

In one embodiment, each gate electrode comprises polysilicon.

In one embodiment, the method further comprising forming active gatestructures simultaneously with the forming at least a duality of dummygate structures, each active gate structure including an active gateelectrode with opposed sidewall spacers and further comprising using theactive gate structure as a mask and forming self-aligned source/drainstructures of a MOSFET (metal oxide semiconductor field effecttransistor) structure utilizing the active gate structure as atransistor electrode.

In one embodiment, the forming self-aligned source/drain structures of aMOSFET comprises introducing source/drain impurities into the substrateusing ion implantation.

In one embodiment, the introducing dopant impurities of a secondpolarity and the introducing dopant impurities of the first polarityeach comprise ion implantation.

In one embodiment, the method further comprises forming a photoresistmask and wherein the introducing dopant impurities of a second polarityfurther comprises using the photoresist mask to cover further portionsof the semiconductor device.

In one embodiment, the method further comprises forming a photoresistmask and wherein the introducing dopant impurities of the first polarityfurther comprises using the photoresist mask to cover further portionsof the semiconductor device.

In one embodiment, each source/drain region is spaced from one the gatestructure by a distance equivalent to a maximum width of a correspondingdummy gate structure disposed over the substrate between thesource/drain region and the one the gate structure.

In one embodiment, the forming at least a duality of dummy gatestructures comprises forming a plurality of the dummy gate structuresover the dopant region, the using the plurality of dummy gate structuresas masks and introducing the dopant impurities of the second polarityinto the dopant region between the plurality of dummy gate structuresthereby forms a plurality of the gate structures, and the method furthercomprises forming a hard mask film extending from and at least partiallycovering adjacent dummy gate structures of the plurality of gatestructures prior to the introducing dopant impurities of the firstpolarity into the dopant region.

The preceding merely illustrates the principles of the disclosure. Itwill thus be appreciated that those of ordinary skill in the art will beable to devise various arrangements which, although not explicitlydescribed or shown herein, embody the principles of the disclosure andare included within its spirit and scope. Furthermore, all examples andconditional language recited herein are principally intended expresslyto be only for pedagogical purposes and to aid the reader inunderstanding the principles of the disclosure and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the disclosure, as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure.

This description of the exemplary embodiments is intended to be read inconnection with the figures of the accompanying drawing, which are to beconsidered part of the entire written description. In the description,relative terms such as “lower,” “upper,” “horizontal,” “vertical,”“above,” “below,” “up,” “down,” “top” and “bottom” as well asderivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,”etc.) should be construed to refer to the orientation as then describedor as shown in the drawing under discussion. These relative terms arefor convenience of description and do not require that the apparatus beconstructed or operated in a particular orientation. Terms concerningattachments, coupling and the like, such as “connected” and“interconnected,” refer to a relationship wherein structures are securedor attached to one another either directly or indirectly throughintervening structures, as well as both movable or rigid attachments orrelationships, unless expressly described otherwise.

Although the disclosure has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodimentsof the disclosure, which may be made by those of ordinary skill in theart without departing from the scope and range of equivalents of thedisclosure.

What is claimed is:
 1. A semiconductor device comprising: a substrate; afirst pair of dummy gate structures disposed over a surface of thesubstrate; a second pair of dummy gate structures disposed over thesurface of the substrate, wherein the second pair of dummy gatestructures is laterally spaced apart from the first pair of dummy gatestructures; a first gate region of a first polarity, wherein the firstgate region is disposed in the substrate and between the first pair ofdummy gate structures; a second gate region of the first polarity,wherein the second gate region is disposed in the substrate and betweenthe second pair of dummy gate structures; a first source/drain region ofa second polarity, wherein the first source/drain region is disposed inthe substrate, and laterally outside the first and second gate regionsand immediately adjacent to one of the first pair of dummy gatestructures; a second source/drain region of the second polarity, whereinthe second source/drain region is disposed in the substrate, andlaterally outside the first and second gate regions and immediatelyadjacent to one of the second pair of dummy gate structures; and a thirdsource/drain region of the second polarity, wherein the thirdsource/drain region is disposed in the substrate, and laterally betweenthe first and second pairs of dummy gate structures.
 2. Thesemiconductor device of claim 1, wherein the first and second pairs ofdummy gate structures each comprises a conductive dummy gate electrodeformed over a dummy gate dielectric.
 3. The semiconductor device ofclaim 2, wherein the conductive dummy gate electrode comprises apolysilicon.
 4. The semiconductor device of claim 2, wherein the firstand second pairs of dummy gate structures each further comprisessidewall spacers along sidewalls of the respective conductive dummy gateelectrode.
 5. The semiconductor device of claim 1, wherein each of thefirst and second gate regions is laterally spaced apart from the thirdsource/drain region by a first link region in the substrate that has afirst length.
 6. The semiconductor device of claim 5, wherein the firstand second source/drain regions are laterally spaced apart from thefirst and second gate regions, respectively, by a second link region inthe substrate that has a second length.
 7. The semiconductor device ofclaim 6, wherein a maximum width of one of the first or second pair ofdummy gate structures is equal to the first length, and a maximum widthof the other of the first or second pair of dummy gate structures isequal to the second length.
 8. The semiconductor device of claim 6,wherein the first length is substantially the same as the second length.9. A semiconductor device comprising; a substrate; a first pair of dummygate structures disposed over a surface of the substrate; a second pairof dummy gate structures disposed over the surface of the substrate,wherein the second pair of dummy gate structures is laterally spacedapart from the first pair of dummy gate structures; a first doped regionof a first conductivity type, wherein the first doped region forming agate region of a first junction-field-effect-transistor (JFET) isdisposed in the substrate and between the first pair of dummy gatestructures; a second doped region of the first conductivity type,wherein the second doped region forming a gate region of a second JFETis disposed in the substrate and between the second pair of dummy gatestructures; a third doped region of a second conductivity type, whereinthe third doped region forming a source region of the first JFET isdisposed in the substrate, and laterally outside the first and seconddoped regions and immediately adjacent to one of the first pair of dummygate structures; a fourth region of the second conductivity type,wherein the fourth region forming a source region of the first JFET isdisposed in the substrate, and laterally outside the first and seconddoped regions and immediately adjacent to one of the second pair ofdummy gate structures; and a fifth doped region of the secondconductivity type, wherein the fifth region is disposed in thesubstrate, and laterally between the other of the first pair of dummygate structures and the other of the second pair of dummy gatestructures, wherein the fifth doped region forms a drain region sharedby the first and second JFETs.
 10. The semiconductor device of claim 9,wherein the first and second pairs of dummy gate structures eachcomprises a conductive dummy gate electrode formed over a dummy gatedielectric.
 11. The semiconductor device of claim 10, wherein theconductive dummy gate electrode comprises a polysilicon.
 12. Thesemiconductor device of claim 10, wherein the first and second pairs ofdummy gate structures each further comprises sidewall spacers alongsidewalls of the respective conductive dummy gate electrode.
 13. Thesemiconductor device of claim 9, wherein each of the first and seconddoped regions is laterally spaced apart from the third doped region by afirst link region in the substrate having a first length.
 14. Thesemiconductor device of claim 13, wherein the first and second dopedregions are laterally spaced apart from the first and second dopedregions, respectively, by a second link region in the substrate having asecond length.
 15. The semiconductor device of claim 13, wherein amaximum width of one of the first or second pair of dummy gatestructures is equal to the first length, and a maximum width of theother of the first or second pair of dummy gate structures is equal tothe second length.
 16. The semiconductor device of claim 13, wherein thefirst length is substantially the same as the second length.
 17. Asemiconductor device comprising: a substrate; and a pair ofjunction-field-effect-transistors (JFETs) that are laterally adjacent toeach other and share a common source/drain region disposed in thesubstrate, wherein each of the pair of JFETs comprises: a pair of dummygate structures disposed above a surface of the substrate; a gate regionof a first polarity disposed in the substrate and between the pair ofdummy gate structures; a source/drain region of a second polarity,wherein the source/drain region is disposed in the substrate, andlaterally outside the gate region and immediately adjacent to one of thepair of dummy gate structures; and the common source/drain region of thesecond polarity, wherein the common source/drain region is disposedlaterally inside the gate region and immediately adjacent to the otherof the pair of dummy gate structures.
 18. The semiconductor device ofclaim 17, wherein the pair of dummy gate structures each comprises aconductive dummy gate electrode formed over a dummy gate dielectric. 19.The semiconductor device of claim 17, wherein the gate region islaterally spaced apart from the source/drain region by a first linkregion in the substrate having a first length, and from the commonsource/drain region by a second link region in the substrate having asecond length.
 20. The semiconductor device of claim 19, wherein amaximum width of one of the pair of dummy gate structures is equal tothe first length, and a maximum width of the other of the pair of dummygate structures is equal to the second length.